A rapid and sensitive method to detect three catecholamines, isoprenaline, epinephrine, and dopamine, by CE coupled with direct luminol-potassium periodate chemiluminescence (CL) detection is described. The conditions for CE separation and CL reaction were systematically optimized. Under the optimum conditions, the baseline separation of three catecholamines was achieved within 6.5 min. The LODs obtained in standard solution were 5.3 x 10(-8) mol/L for isoprenaline, 4.7 x 10(-8)mol/L for epinephrine, and 1.5 x 10(-7) mol/L for dopamine. The RSD of the migration time and peak area were less than 1.8 and 3.6% (n = 5), respectively. The present method was applied to the determination of the dopamine in urine samples of cigarette smokers and nonsmokers. The results obtained indicate that there is a dose relationship between the content of dopamine in human urine and the amount of cigarettes smoked daily; the level of dopamine in smokers is higher than in nonsmokers.